This invention relates to improvements in motor operated pumps. The improved pump of the instant invention was specifically designed to be used as a component of a system for supplying fluid pressure to a system of tourniquets. In this environment it is quite important to be able to pump very low volumes of fluid to the tourniquets and to be able to pump quite low differential pressures. Prior art pumps known to applicant were not able to satisfy these criteria under very careful testing. The two pumps tested by applicant were a Romega 080 pump and a pump manufactured by K & F Neuberger.
Also known to applicant are the following U.S. Pat. Nos.:
3,058,140 to Henss shows a collapsible wall pump including as best shown in FIG. 4 a valve plate including two valve members 8 cut out therefrom. Depressing of collapsible wall 2 and successive expansion thereof causes a pumping of fluid from inlet direction a, to outlet direction b, through port 6.
3,134,125 to Kaiser discloses a pump which as best shown in FIG. 11 includes a valve plate 86 with valves 86a and 86b cut out therefrom. As best shown in FIG. 7, the pump, through the valve plate 86, controls flow from inlet 90 to outlet 92.
3,371,852 to Holt discloses a motor operated pump including as best shown in FIG. 7 valve plate 40 with valves 43 and 44 cut out therefrom. FIG. 5 shows the configuration of the valve plate 40 when mounted in its housing.
3,545,894 to Lovitz discloses a pump including as best shown in FIGS. 8 and 9 a single valve plate with two valves cut out therefrom. The valves control the supply and exhaust from a chamber in said pump.
4,181,477 to Litt shows as best seen in FIGS. 1 and 2 a diaphragm motor operated pump which includes a resilient valve plate 30 out of which slots 62 are cut to form valve members 60. The configuration of the valve plate 30 in the housing is best shown in FIG. 1 and includes opposed valve seats to control supply and exhaust of fluid to and from chamber 26.
Other patents known to applicant but considered less relevant than the above discussed patents are U.S. Pat. Nos. 1,619,481 to Oakes, 2,559,067 to Doeg, 2,638,849 to Budlane, 3,360,169 to Susuki, et al., 3,703,342 to O'Connor, 3,998,571 to Falke, and 4,099,544 to Itakura, et al.